Quench oil

If I'm remembering correctly, its not as fast as parks 50, which I believe is considered a 9 second oil.

Personally for the two steels you mentioned, I'd want to use parks 50 or an equivalent.
 
If I'm remembering correctly, its not as fast as parks 50, which I believe is considered a 9 second oil.

Personally for the two steels you mentioned, I'd want to use parks 50 or an equivalent.
You've remembered correctly. This oil is 11 second oil.
What is a better equivalent to the parks 50?
 
Truly fast oils are in the 7-10 second range, while medium speed are 11-14 second. Park Metallurgical/Heatbath #50 is 7-10, Park Metallurgical/Heatbath AAA is 11-14 second. The McMaster oil would be more like Houghton quench “G” which is 11-14 second. Houghton makes a type “K” that is faster and more like the #50.

Normally the 11-14 second oils would be too slow for 10XX like 1084, but I would ask how think are your knives? If they are typically 3/16” or less at the spine you may be able to get away with the McMaster Carr oil. What you will get when the oil can’t quite meet the speed requirements of the steel is increasing amounts of pearlite as the cross section increases. So, your edge will be mostly martensitic and you will get increasing amounts of pearlite as you move towards the spine, and when the pearlite becomes predominant you will start to form auto-hamon features.

So, if you are very fussy about complete, thorough and consistent, results then you will be bothered if you don’t have complete martensite transformation in the blade body and spine. But many folks have no problem with only the first 3/8” of the edge side being fully hardened, as is evident by the ubiquitous nature of hamons on knives these days.

It is worth noting, however, that if you are intentionally going for hamon, you will want the fast oil as the clay moves the cooling curves significantly.
 
My limited experience and reading tells me that the medium speed 11-13 second oil Is a bit more sensitive to pre quench temperature. My understanding is that a few years back, parks adjusted the formula of #50 so that it effectively works at “room temperature” aka anything from 70F up to the low 100’s. My reading leads me to believe that the slower oils like the AAA or the Houghton, which is also repackaged as Brownell’s tough quench last time I checked, is an 11 to 13 second oil depending on the starting temperature. My recollection from using it is that the recommended ranges from around 120 to 180 and at the the lower and upper range, it’s a 13 second oil, but at the “sweet spot” of 150 or so, you get the 11 second performance. I have a 5 gallon bucket of that McMaster Carr oil and to me, it looks nothing like the tough quench to the eye, so it may have been sourced elsewhere. The performance seems to be pretty much identical.
 
Check out the data sheets on this I asked about awhile back. Particularly the Enquench Medium 2.

 
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